The breakfast room of Madrid’s Westin Palace hotel is tennis heaven. On the carpet where Salvador Dalí once paraded his pet ocelot on a gold chain, Kim Clijsters leaves a late breakfast clutching bread rolls. Billie Jean King pads about in giant multicoloured sneakers. And at nearly noon, even Martina Hingis is up. To eat here, beneath the art nouveau cupola, signifies having made it.

Twelve months ago Hingis, only 25, had been retired from tennis for three years. In January the best child player in tennis history returned to the game. She entered the Australian Open ranked 349th in the world and at season’s end, here she is, playing in the Sony Ericsson championships for the best eight female players on earth. Outside, Madrid in November provides perhaps the ideal climate for human habitation. All would be perfect, except that it still looks as if Hingis peaked aged 17. Can she live with that?

The “Swiss Miss” perches on the sofa – at 5ft 7in, she is a Smurf on the women’s tour – and does her apple-cheeked grin. In a great year, what was the best moment? Hingis eats fruit salad and thinks. “Probably now. Somehow making it here and having Radek here, trying to help me,” she says in the teenage American-English that is the tour’s lingua franca. Radek Stepánek, the Czech tennis player, is the latest in a line of Hingis’s athletic boyfriends that includes Sol Campbell and Sergio García.

“Hi Billie Jean!” she greets, then continues: “Probably against Nadia, that was the best match ever I’ve played. Did you see it?” Two evenings before she beat Nadia Petrova for her only victory at the championships. Hingis hopes this will break her psychological block against the best players. “I had so many chances against Amélie [Mauresmo] or other players throughout the year and I wasn’t able to convert it because I’m like: ‘I’ve only just come back, can I really beat the top players again?’ ”

She never used to have that problem. At 16, Hingis had already won three singles titles in Grand Slams. She was then rarely seen without her mother, Melanie Molitor, who had begun coaching her aged two. “From the minute I woke up the whole day was scheduled,” recalls Hingis. “My mom raised me that way: ‘Whatever you do, you’d better just do it right.’ Whether I was skiing, swimming, aerobics, horse-riding, trampolining.”

Hingis believes it had to do with their being immigrants to Switzerland from Slovakia. “The desire to succeed, it definitely pushes you more than when you already have everything the country has to give. Even Roger [Federer] isn’t a real Swiss. His mother is [South] African, right? But I’m proud the country gave me the chance. Not even in a dream would I say something bad against it.”

The young Hingis produced tears, tantrums, and taunts – she called the lesbian Mauresmo “half a man” – but she also made friends in tennis. She singles out her former doubles partner Anna Kournikova: “With Anna, those were some of the best years I spent on tour. We had similar interests, we were the same age. She was a hard worker, she had the team spirit.” (Please suppress gasps here.)

In 2003 Kournikova and Hingis both abandoned tennis. Hingis blamed foot injuries but also a fear of missing life. Her “retirement”, with hindsight, was the mid-career sabbatical that exists in no sport but tennis. Players start work as toddlers apprenticed to perfectionist parents and burn out in their early 20s. The Williams sisters took sabbaticals and never quite returned. Andre Agassi realised on sabbatical that tennis was his vocation. So, it seems, did Hingis.

In retirement, she competed in showjumping and studied business English but, perhaps, her greatest achievement was washing clothes. “I was happy when for the first time I did the laundry. I cooked a meal and I survived. I’m like, ‘Hey, I can walk up straight, with my head up high!’ ” She had become an adult.

Suddenly Hingis is scarfing something other than fruit salad. Is that thing in her hand really a chocolate? She issues her trademark giggle. “It’s my day off. We don’t have an off-season that long. Week in week out, you’d go crazy if you don’t sometimes treat yourself.”

Her comeback has been brilliant. In her first tournament of 2006, on Australia’s Gold Coast, she reached the semi-finals in both singles and doubles. Dee Dutta, global head of marketing for Sony Ericsson, the sponsor of the women’s tour, also in the breakfast room, crows later: “We need stars. Martina’s one of the biggest lights in a year when Serena and Venus [Williams] have not been able to shine as brightly, and there is only Maria [Sharapova].”

Some say women’s tennis is in trouble when a player can shoot back to the top after three years off. Hingis retorts: “Technically and mentality-wise, I was not for no reason number one for four years.”

Has tennis broken her body? Hingis ruefully quotes a German saying: “Sport ist Mord” or “Sport is murder”. Then she adds: “I would never complain being a tennis player, not even a second. My mum was saying sometimes, when I wasn’t into practice, ‘Go and be a cashier in a supermarket.’ I think nobody asks those people what they’re going to do, how they feel after they’ve finished their job.”

Given her size, can she ever return to number one? Hingis points out that giant-slaying has been her life. As a child she always played much older girls, winning the French Open under-18s title at 12. “My mom found a way for me to beat the big girls. I never had to play with size or power, but smartness.” She squares her shoulders: “Everybody says I’m stronger now. You become a woman.”

In fact she probably did peak at 16, and will probably never be number one again, but at least she now plays because she wants to – and can wash her clothes.